And answering to myself, it seems this issue has already been fixed, sorry for the noise.
Rémi ----- Mail original ----- > De: "Remi Forax" <fo...@univ-mlv.fr> > À: "dev" <dev@groovy.apache.org> > Envoyé: Mercredi 13 Février 2019 11:50:45 > Objet: JsonSlurper doesn't work with Java 9+ > This was reported on the Java bug tracker but it's a Groovy issue (a > groovy-json > one), > > https://bugs.openjdk.java.net/browse/JDK-8218540 > > The JsonSlurper has not being updated to work with the new Java 9 String > implementation that uses an array of bytes, containing either a 8 bits > representation or a 16 bits representation, instead of an array of chars. > > cheers, > Rémi